Step 1

Combine tomatoes, scallion whites, cilantro, garlic, chipotle, and ¾ teaspoon salt in bowl; set aside.

Step 2

Combine shrimp, ¼ teaspoon salt, and ¼ teaspoon pepper in separate bowl. Heat 1 tablespoon oil in 12-inch nonstick skillet over medium-high heat until just smoking. Add half of shrimp to pan in single layer and cook, without moving them, until spotty brown and edges turn pink on bottom side, about 1 minute. Flip each shrimp and continue to cook until all but very center is opaque, about 30 seconds. Transfer shrimp to large plate. Repeat with remaining 1 tablespoon oil and remaining shrimp.

Step 3

Return skillet to medium-high heat. Add tomato mixture and lime juice and cook until tomatoes soften slightly, about 1 minute. Stir in shrimp and cook until shrimp are cooked through, about 1 minute. Transfer to platter and sprinkle with scallion greens and avocado. Serve with lime wedges.